Technical Field
Technology disclosed herein relates to a vehicle pop-up hood device actuator that lifts a vehicle hood, and to a vehicle pop-up hood device.
Related Art
Japanese Patent Application Laid-Open (JP-A) No. 2013-71544 describes what is known as a piston cylinder type actuator that lifts a vehicle hood. Specifically, the actuator is configured including a tube shaped cylinder, and a piston rod housed inside the cylinder. A piston portion of the piston rod is provided with a lock pin. When a gas generator provided in the cylinder is actuated, the piston rod rises with respect to the cylinder by the gas generated by the gas generator, thereby lifting the vehicle hood. When this is performed, the lock pin anchors to an anchor face of the cylinder, and the piston rod is retained by the lock pin. The lifting of the hood is thereby retained, protecting a pedestrian falling onto the hood. Note that an actuator that lifts a vehicle hood is also described in JP-A No. 2014-133535.
If high pressure gas remains inside the cylinder after actuation of the actuator, a reaction force from the hood acting on the pedestrian falling onto the hood could increase, thereby raising the pedestrian injury criteria. Forming gas escape holes in the cylinder to release high pressure gas inside the cylinder, for example, may be considered in order to reduce the reaction force on the pedestrian from the hood.
However, when gas escape holes are formed in the cylinder, there is a possibility of a lock pin catching on the peripheries of openings of the gas escape holes when the piston rod rises with respect to the cylinder during actuation of the actuator. There is accordingly a need for high assembly precision of the actuator in order to prevent the lock pin from catching on the peripheries of the openings of the gas escape holes. In other words, it is desirable for the actuator have a structure in which the effect of assembly precision on actuation is suppressed.
An exemplary embodiment of the present invention provides a vehicle pop-up hood device actuator and a vehicle pop-up hood device capable of lowering pedestrian injury criteria, while suppressing the effect of assembly precision on actuation.